I own a note 3 smn900.......no back button vibration plus call button lag

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AC Question

I own a samsung note 3 smn900.......I've been noticing no vibration on clicking the back button.......trust me I've tried everything......nd I'm a coder myself........this is an on n off problem not a continuous problem.........I'm fed up with the call button lag n with sammy.......clearing the ram works........but an hour after clearing the ram, there is a distinct 2 second lag........with auch a peice of hardware I'm expecting zero lag